Sapety-valve



(Model) 7 P. B. SCO'VELL.

Safety Valve.

. No. 239,985. Patented April 12,1881.

R U T N E V N l WIT N E55 E5 N. PETERS. PHOTO-LIYHDGRAF UNITED STATES PATENT OFFICE.

FRANK B. SOOVELL, OF BOSTON, MASSACHUSETTS.

SAFETY-VALVE.

SPECTFICATION forming part of Letters Patent No. 239,985, dated April 12, 1881.

Application filed November 9, 1880. (ModeL) that class of valves knownas quick-relief valves. These valves involve gre'at nicety of detail of construction, which renders them liable to get out of order under continuous use.

Safety-valves of the ordinary construction, as

is well known, are very restricted in their action, lifting very slightly off their seats, and the pressure often increasingrapidly after the valve has risen.

The object of my invention is to produce a valve of the class above named of simple mechanical construction, and in which seats of the common type are used; and the invention consists in the combination, with a main valve arranged in one compartment of a shell or casing, of a separate and independent valve in another compartment of the said casing, the two compartments being connected by a pas sage leading from one to the other.

The invention further consists in the peculiar construction of the main valve and its connections.

Referring to the drawings, Figure 1 represents an elevation of a valve embodying my improvements. Fig. 2 is a vertical section of the same. Fig.3 is abottom view of the main valve. Fig. 4 is a top view of the same.

A A represent the casing, comprising two compartments united at the lower part, into which steam enters through the passage B.

E is the main valve in compartment A, and M is an auxiliary valve in compartment A.

O G are valve-spindles fitted to the valves E and M, and'each encompassed by a spring, 0 a, bearing respectively at their lower ends against disks 6 e, secured to the spindles, and at their upper ends against disks orrings d d, placed loosely on the spindles, the said disks or rings bearing against the under sides of the screw-caps D D, which compress the springs, and by means of which the resistance to the lifting action of the steam is regulated.

E represents the mainvalve, located in compartmentA and fitted in chamber I. The face a disk or piston on the upper end of valve M,

and O O are guides attached to the same. The valve M is seated at P at its lower end.

L is a passage between the two compartments and communicating between the two valves.

T T in Fig. 1 are openings in the casings A A for the exit of steam to the atmosphere. The operation is as follows: Steam, being admitted through the opening B, passes into each of the compartments, the two valves bein g in their statical condition, and the pressure acts upon both valves. The main valve is designed to relieve the boiler of its excess of pressure, and when the pressure exceeds the resistance of the load the main valve will rise off its seat, in which case the steam will escape into the atmosphere, passing through the interior and exterior seats, F G. At this time, suppose the pressure to be one hundred and five pounds on the main valve and the auxiliary valve has been adjusted to open at one hundred pounds, the action of the latter would be as follows: On rising off its seat it permits steam to pass around and above it, the consequence being that a pressure forms as soon as the opening of its seat becomes greater than the leakage of the pistons or disks of both valves. The pressure exerts itself on the under surface of the disk or piston of the main valve, and consequently tends to increase its lift off its seat, thereby relieving the boiler of its excess of pressure. It will be understood that the pressure created after the-auxiliary valve rises from its seat is the same between the disks or pistons of the main and auxiliary valves. A certain amount of leakage occurs before any pressure is formed, as the steam will, to a certain extent, pass through the piston of the auxiliary valve into the atmosphere, and likewise through the piston and the interior opening of the main valve into the atmosphere.

So far as the adjustment of the two valves is concerned, it will be seen that if adjusted to open at or near the same pressure the resistance of the main valve would be quickly overcome by the additional action of steam underneath it from the auxiliary valve.

Trip-levers can be connected in a variety of ways for the purpose of lifting the valves by hand, and also lock-updevices can be attached, to accomplish which the two spring cases and covers should be connected to prevent them from being revolved.

While the drawings illustrate steam acting under the central portion of the main valve, which comes from the compartment of the auxiliary valve, I do not confine myself exclusively to such an arrangement, as the main valve might be constructed in connection with an annular rim around the outer portion of the "main valve, acting in a chamber into which steam can be admitted from the auxiliary valve, and produce the same result. I have also constructed a valve in which steam is admitted to a compartment located above the main valve, into which steam from the auxiliary valve enters and creates a pressure under a disk or piston surrounding the spring-spindle, and which holds the spring, the said pressure being kept off the top of the valve by means of a fixed partition, through which the spindle passes to reach the valve beneath, and steam escapes under this partition outward above the valve through the side of the chamber.

Weights can be substituted in the place of springs to form the load, if desirable.

It will be seen that the interior and exterior seats of the main valve are each subject to the same duty, and consequently will receive an equal amount of wear.

In the operation of my improved valve there is an especial feature relative to the advantages of adjustment. By fixing the auxiliary valve at any desired pressure the lift of the main. valve will decrease in proportion to the amount of resistance at which its load may be increased over that of the auxiliary valve, although the opening of the main valve might be somewhatincreased thereby. A perfect adjustment can easily be established by increasin g or diminishing the resistance of both valves to attain the desired result.

What I claim as my invention is 1. The valve E, constructed with a piston or disk, H, fitting in chamber I, and provided with interior and exterior bearin g-surfaces and openings, S, substantially as and for the purpose specified.

2. In a safety-valve, the combination of the auxiliary valve M, the passage L, extending from a point between the seat P of the auxiliary valve M and its disk N above to the chamber I, containing the piston H and the main valve E, substantially as and for the purpose set forth.

In testimonywhereof I have signed my name to this specification in the presence of two subscribing witnesses.

FRANK B. soovELL.

Witnesses:

J. H. ADAMS, J. J. MCCARTHY. 

